Method of preserving avocados



Patented June 9, 1953 METHOD OF PRESERVING AVOCADOS Helen w. Heinrich, Little Rock, cant.

No Drawing. Application April 6, 1950,

Serial No. 154,440

4 Claims. 99154) 7 '1 This invention relates to a method of preserving avocados, and the product resulting therefrom. The application is a continuation-in-part of my prior application Serial No. 116,627, filed September 19, 1949, entitled Method of Preserving Avocados.

A primary object of the invention is to pro-' vide a method by which the meat of an avocado fruit may be preserved for future use wherein the product obtained from the use of the method retains the flavor andother characteristics 'of the fresh fruit.

More specifically, an object of the invention is to provide a method of preserving avocado meat which can be optionally used to preserve the. meat for a period of from four to six months without canning it in hermetically sealed containers, or which can be used to can the meat in such containers so as to be preserved indefinitely.

In districts where avocados are raised many attempts have been made to preserve the meat of this fruit. Climatic conditions frequently are such that the entire crop will ripen'very quickly and while the ripening of the fruit after it has been picked can be somewhat postponed or delayed by packing each fruit separately and maintaining it in a cool dark place, nevertheless the ripening proceeds rather rapidly. It is consequently highly desirable to be able toallow the fruit to ripen normally and to be able to preserve the meat of the fruit for future use. Heretofore attempts have been made to preserve avocado meat but such attempts have generally proven unsuccessful due to thefact that the resulting product has a decidedly different flavor from that of the fresh avocado.

Essentially, the present method consists of blanching or scalding the freshavocado meat in an edible vegetable oil for approximately one minute at a temperature of approximately 220 F. although temperatures below and above this preferred temperature may be employed as hereinafter explained.

In preserving the avocado meat in the form of an avocado butter such as is used as a spread, the fruit is peeled and the seed or pit removed. The meat is mashed into the form of a paste. This mashed meat is then quickly introduced into an edible vegetable oil that has been heated to a temperature of approximately 220 F. and is rapidly stirred therein for a period of about one minute. I prefer to use a vegetable oil which, if it has a flavor, iscompatible with that of the flavor of the avocado meat. Many vegetable oils for all practical purposes may be regarded as substantially flavorless. After the meat has been thus'treated it is removed and placed in a suitable storagecontainer and can be stored from four to six months if maintained at a relatively cooltemperature which will greatly retard, if not prevent, the oil from turning rancid. This form of product can be kept in an open container, that is one which has not been hermetically sealed, in a refrigerator or cooler or can even be frozen.

In preserving quarters or diced pieces of the avocado meat these pieces are immersed in the edible vegetable oil, heated to a temperature of about 220 F. for approximately one minute.

Thereafter, they may be removedand placed in jars and covered with the oiland similarly kept.

In' my prior. applicationab'ove referred to I was ofthe belief that com oilwas the only suitable oil for my purpose. Further experimentation, however, has disclosed that the temperature of the blanching oil need not be as high as 220 F. but-may be as low as F. Temperatures above 220 v F-.; may be used if the avocado meat is agitated or stirred sufliciently to prevent scorching. In view of the fact that this range of temperatures is permissible, I find it is possible to use any-edible vegetable oil which is either flavorless or which has a flavor compatible with that of the avocado and which will not break down or darken objectionably when heated to-"the blanching temperatureof 185 F. or above; Corn oil is quite-suitable, but in addition thereto, cottonseed oilwhich has been freshly refined is also suitable. Soy bean oil can be employed at a relatively low blanching temperature but at high temperatures such as 220 F. soy bean oil has a tendency to breakdown and darken objectionably. Even avocado oil may be employed. v

In my prior application, above-mentioned, Wesson oil which is primarily cottonseed oil and peanut oil were mentioned as being objectionable due to their rapidly turning rancid. I find however that many cottonseed oils placed on the market have been allowed to remain stored in their containers" for long periods of time before being used. These cooking oils marketed as such frequently contain small amounts of antioxidants or oxidizing inhibitors designed to retard or prevent the oilfrom turning rancid during prolonged periods of storage. Nevertheless, although such vegetable oils are thus equipped with the oxidation inhibitors they approach turning rancid in their containers during storage so that at the time of use they may be in such condition that on being used in my process they may turn rancid rapidly thereafter.

In my process, if such oils as cottonseed and peanut oil are freshly prepared they may be used to advantage with or without an antioxidant or oxidation inhibitor. I find also that some olive oils are obtainable which have been so refined as towbe almost flavorlessaand these oils maybe used without imparting an objectionable flavor to the avocado meat. The proportion of oil used to the avocado meat is not critical, being in the neighborhood of one-part oil to three parts of avocado meat, or one part oil to four parts meat. considerably.

In performing my process I 'find' it advantageous to add to the oil an anti-oxidant or oxidation inhibitor that will not only retard-rancidity in the edible vegetable oil used, but will also retard the avocado oil. inherentlypresent :in the avocado meat from .oxidizing 1 ort-tu-rnihg rancid. Even if I the oil-.employed-is. arcommercial product. containing-an anti-oxidant? or oxidation inhibitor it is desirable inemostin stances, butnot invariably so, toadd anantioxidant or oxidation. inhibitor. This. added inhibitoriseffective upon the avocado oilinherently present in the avocadoi meat. .Some oxidation inhibitors that havebeen successfully employed are '(l) Nordihy'droguaiaretic. acid, a recommended proportionof which is approximately .005%- '(2) .But'ylated'..hydroxyanisole, a recommended ,proportionbeing .01.%. to .02 by weight. (3)".Sustane, a hi'g-h1y purified grade.v of tertiary butyl liydroxyanisole. whichis mixture of two .isomers with Beter'tiary butyl.41-hydroxyanisole,

.themore, potent. isomer predominating.

This product is furnished in three forms (a) as a crystal and solid in-whi'ch'the -recommended proportionis ab'out";01%.

(b) In a 30% solution in lard oil in-Whi'ch case I use a recommended proportion of about 1 pound to three thousand'poun'ds of my product. p

(c) In a solution of propyl'gallatehaving-approximately the following composition:

- Percent rButyl .hydroxyanisole 1.20 Propylgallate 16 Citricacid 4 Propylene glycol 70 The recommended proportion of meanhibitor is about one" pound to two-thousand pounds of my product. (CD The anti-oxidantdisclosed'iir'UL SFL etters PatentNo. 2,464,927. Of 'this' ariti oxi' dant; two ounces to fourounces is 'used per one'hundred pounds of my'prod'uct.

Other oxidation inhibitors maybe employedi'in lieu of those" mentioned which will. prevent? or retardthe vegetable oil used and/or. the. avocado oil inherently present in' 'thef meat from rapidly turning rancid.

I find it is'relativelyiimportant try-heat! the avocado 'meat as fast: as isrreasonably .possible to' a point above. 180 'F; in 'orderwto. prevent. the avocado meat from acquiringa .bittereflavor. This is particularly" true if' 'the product is'tobe subsequently canned Tin hermetically-sealed containers which, in accordance with.some-State These proportions may i vary duced to a minimum. Consequently, it is highly desirable-to. raise the temperature of the avocado meat as rapidly as reasonably possible in order that" the timeduring which conditions are most favorable to.the enzymes may be reduced to a minimum. For this reason, it is frequently desirable to pass the avocado mash into the hot oil'in the form of thin layers so that the meat composing the layer can be quickly brought up tothe temperature of..the. blanching oil.

It.-is of. some importance to employ the proper type-of containersin which: the blanching or scalding: takes place; ..I have found that. stainless steel. of" the character conventionallyemployed for cooking vessels is suitable. Vessels of glass, porcelain, orr granite ware may beemployed. The-1 stirring.andahandling.:of the avocado meat isi'preferably; accomplishedwvith a wooden. spoon. I find that if the. container in which. the blanching or scalding takes place/is madeiof: aluminum or if the stirring implement is made of aluminum that this: metal seems to .imparta disagreeable metallic flavor: to. the.-.avocado meat. The-. use of; copper'vessels or. copper implements, is to: be avoided as: this..metal -will ..-detrimentally' afiect the. color of the-meat by turning it dark.

The" containers :imwhich the. treated. meatis kept shouldalikewise be either -of.- stainless 1 steel or of a non-metallic character such asgfglass, porcelain; or the like. Cans: that have been'in- .ternally" treated. so as to be suitable for cannin fruitszhowever can be employed.

.YA feature of. the present :proeess. :is. that the blanching. or scalding operation With lthe ve'getable; oilseem 'toreturn to the meat-its desirable bright green color; ..If-the avocado most used is. somewhat 1 yellowish in its natural state, as frequently occurs when lthe. fruit is vslightly'overripe, the blanching seems to restore-to themeat its' bright. green color.

I The delicatevfiavor of; theavocado meatmay be accentuated or intensifiedby the additionpof ax small; amount of. flavor-iaccentuator such as monoa-sodimn glutamate.

".'The;aavo.cador;meat 'Ethus; blanched or scalded may be: kept; for: at period? of four to: sixs months in an: openv container in. a: cooler .or. refrigerator. However; whenjtiis desired. to: preserve the; meat for? an .iridefirrlte-leng-th of time the pro duct-:may bet; place-din? containers and; hermetically sealed therein; such as byiheat' sealing asin homezcanning. -For =canning'=plant production the meat may be placed in suitable containers and heated in pressure cookerfor the required time of eightyirninutes at 240 "This. procedure; however; tends to'lighten the color-of thewproduct.

wInstead; ofr' hermetically sealing: .the blanched avocadmmeat' in: cans. or similar receptacles the product may be kept indefinitely:also-byfreezing' it'in any of theconventionalemannerswherein deep=frozenfoods are preserved.

It will be found that the resulting producthas a; flavor. as -Well as: other. characteristics. very close tothat of the fresh fruit,, particularly. if

the blanching oil is either flavorless or has a flavor compatible with that of the avocado oil. Various changes may be made in the method or procedure herein disclosed within the scope of the invention as defined by the appended claims.

Iclaim:

1. The method of'preserving avocado meat which includes blanching the meat in an edible vegetable oil for about one minute at a temperature of from 185 F. to 220 F.

2. The method of preserving avocado meat which includes introducing the meat into an edible vegetable oil and rapidly bringing the temperature of the meat to a temperature of from 185 F. to 220 F. and maintaining it at such temperature for about one minute.

3. The method of preserving avocado meat which consists of blanching the meat in an edible vegetable oil to which a small amount of oxidation inhibitor has been added for about one min- 6 ute at a temperature of between 185 F. and 220 F.

4. The method of preserving avocado meat which consists of blanching the meat in an edible vegetable oil to which a small amount of oxidation inhibitor has been added for about one minute at a temperature of between 185 F. and 220 F., then placing the meat and oil in hermetically sealed containers and cooking at 240 F. for eighty minutes.

HELEN W. HEINRICH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 769,737 Gardner Sept. 13, 1904 1,377,088 Martin May 3, 1921 20 2,315,858 Johnston et a1 Apr. 6, 1943 2,485,635 Neal Oct. 25, 1949 

1. THE METHOD OF PRESERVING AVOCADO MEAT WHICH INCLUDES BLANCHING THE MEAT IN AN EDIBLE VEGETABLE OIL FOR ABOUT ONE MINUTE AT A TEMPERATURE OF FROM 185* F. TO 220* F. 